This is a new application for training grant support with a single mission: the goal of this T32 program is to train physicians who will be the future academic leaders in basic and/or clinical pediatric oncology research. Reducing the burden of cancer in the pediatric population requires necessitates research across the entire spectrum from fundamental molecular and cellular biologic studies to translational work that bridges the gulf that separates basic research and clinical medicine to clinical investigation. Reducing the burden of cancer in pediatric populations requires broad and intensive training of academic pediatric physicians. An experienced and highly accomplished group of faculty including faculty of the Department of Pediatric Oncology at the Dana Farber Cancer Institute (DFCI), the Division of Pediatric Hematology/Oncology at Children's Hospital Boston (CHB), and additional components of the Harvard Medical School constitute the training faculty for this program. This faculty encompasses basic, translational, and clinical investigation. Trainees will be selected from the combined DFCI-CHB pediatric hematology/oncology fellowship program. Particular emphasis is placed on close mentorship of trainees in the selection of mentors and in on-going oversight during their research. The program is committed to identifying and supporting the most promising fellows, including minority candidates. Over the past 40 years the DFCI-CHB fellowship program has trained >200 individuals, many of whom are leaders and academic pediatric medicine. The proposed T32 program will ensure the continuance and further development of the fellowship program, and promises to contribute immeasurably to the management of children with cancer. While great strides have been made in diagnosis and treatment of pediatric cancers, much remains to be done. Cure of patients is often achieved with unacceptable side-effects, and for many solid tumors current therapy is inadequate. The best hope for reducing the burden of pediatric cancer is the training of committed researchers by an experienced and accomplished faculty that is involved in diverse aspects of basic and clinical research directly relevant to tackling these challenging problems in children.